Final answer:
Dr. Martin Luther King Jr. is using the rhetorical device of parallelism in his "Letter from a Birmingham Jail" where he contrasts two ideas for emphasis.
Step-by-step explanation:
Dr. Martin Luther King Jr. is using the rhetorical device of parallelism.
Parallelism is the use of similar structures or patterns in a sentence or paragraph to emphasize or compare ideas. In this excerpt from his "Letter from a Birmingham Jail," King contrasts the idea of creating tension in the mind for individuals to rise from bondage to the realm of creative analysis and objective appraisal with the need for nonviolent gadflies to create tension in society to help men rise from prejudice and racism to understanding and brotherhood.
Through this parallel structure, King highlights the importance of tension and disruption in promoting social progress, using the example of Socrates' belief in creating tension in the mind to challenge myths and half-truths. This rhetorical device enhances the persuasive impact of King's argument.